RU2491407C2 - Rolling bit with sealed support - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: rolling bit with a sealed support comprises legs, lubrication reservoirs tightly installed and rigidly fixed in them, elastic membranes with a radial and end metal frame, end circular centring washers, end pressing elements, conical threaded plugs, side bores on walls of reservoirs with through holes for lubricant release from the cavity of the reservoir into the lubricating system, and also a system of channels and holes for supply of a drilling mud under elastic membranes. At the side of release from seats in legs there are adjustment and stop nuts installed on the thread with holes at the ends for a socket wrench, which control forces for clamping of the elastic collar of the membrane, the end clamping element and the threshold of actuation of excessive pressure relief in the system of bit lubrication.

EFFECT: improved reliability of operation of rolling bits, their reservoirs, possibility to adjust a threshold for actuation of excessive pressure relief with regard to depth of suggested drilling interval.

Description

The invention relates to the field of drilling equipment and is used in the construction of wells in deep and super deep drilling.

For reliable operation of the sealed cones in the bits for deep drilling in the paw bodies, reservoirs are provided for accommodating the lubrication system, the device of which provides the supply of lubricant to the friction zone in the supports as it is consumed during drilling.

A known design of the cone drill bit with a sealed support [1], consisting of the following elements. A steel cover with a system of holes in the upper protruding part connecting the annular space of the bit with the outer surface of the elastic membrane fixed under the cover is installed in the cavity of the reservoir socket using the locking ring. When pressure fluctuations in the well during the operation of the pumps, the membrane in the tank periodically straightens and pushes part of the lubricant from it first into the supply channel system, and through them into the friction zones of sliding, rolling bearings or their combination in bearings. Sealing of the lubrication system in cones is carried out by elastic rings, and on the side of the bit nipple - by a welded cork. From rupture of the elastic membrane at its maximum turn, a steel cup is provided, the inner borders of which are the calculated maximum dimensions for the swelling membrane. For the same purpose - to prevent tearing when approaching the hole in the glass, a rubberized metal “patch” is provided on the top of the membrane, which prevents the rupture of the top part. An annular rubberized collar of an elastic membrane mounted on a ledge of a socket is a sealing element for both the membrane and the cover. Filling with grease is carried out after evacuation of the internal cavity of the membrane and the supply channels of the system.

On the side of the long underwater channel in the paw, a breathing channel is installed, which relieves excess pressure in the lubrication system during the operation of the bit. The disadvantage of this design of the reservoir, adopted as an analogue, is the small volume for the reserved lubricant, as well as the sluggish operation of the membrane when clogged with slurry holes in the lid and weakening pressure fluctuations in the annulus.

There is another design variant of the cone drill bit with a sealed support, adopted for the second analogue [2]. In this embodiment, the volume of the grease nest is slightly increased, and the action pattern of the flushing fluid on the membrane and lubricant during drilling is changed. The hole in the body of the paw, connecting the membrane with the annulus, is transferred from the outer surface of the housing to the inner, suprahepatic surface. This made it possible to increase not only the amount of lubricant, but also the pressure difference above and below the membrane, since the hole is close to the outlet of the flushing nozzle, where the fluid pressure is slightly higher than in the first analogue. The shape of the overall cup, lid and the sealing scheme of the membrane and lid in the socket have also been changed. The scheme for supplying lubricant from the reservoir to the bearing working areas in the bearing, as well as relieving excess pressure using the side valve on the side of the foot, remained the same. The main disadvantage of this second analogue is that, like the first analogue, it is not able to regulate the amount of overpressure in the support.

Known for another roller cone bit with a sealed support, adopted as a prototype [3].

Unlike both analogues, a steel disk spring is used in the design of the tank with a sealed support, which ensures that, with an internal overpressure in the support, it is balanced with the pressure of the flushing fluid in the same region as in the second analogue, in the suprahepatic space of the sections. As soon as the internal pressure in the lubricating system exceeds the spring pressing force, it is pressed together with the membrane and centering washer from the flat stop face inside the tank, opening a flat gap along the said stop face and the radial gap between the inner wall and the radial parts of the membrane and the centering washer, in in turn, connected with the help of gaps and channels with supraherosal space of the bit. Overpressure is released along with part of the lubricant. When the pressure is balanced, the spring force closes the gap until the next compression cycle.

The disadvantage of the prototype is the inability to adjust and also set the desired value of the pressure discharged from the reservoir and the support at various drilling depths, since the position of the expandable retaining ring installed on the outlet end of the reservoir closes and fixes only one position of the inserted reservoir and the compressed disk cup spring, and it means that it can operate only at one pressure value in the support, at which the onset of operation is possible.

The fact is that the prototype does not take into account the effect on the operation of the reservoir for the lubrication system of the drill bit changes in the depth of the intervals of drilling. The greater the depth, the less elastic the membrane material becomes. It is embrittled and undergoes much faster wear under cyclic loading.

The technical result of the present invention is to increase the reliability of the reservoir, as well as the ability to adjust the threshold for the release of excess pressure in relation to the depth of the proposed drilling interval.

The specified technical result is achieved by the use in a cone drill bit with a sealed support of the reservoir for a lubricating system, comprising a housing sealed and rigidly fixed in the hole of the paws, an elastic membrane with a radial and end metal frame, an end ring centering washer with a central hole, an end pressing element for providing a clamping of the membrane, a conical threaded plug for the introduction of lubricant, a side groove on the wall with through holes for ode lubricant from a reservoir cavity in the lubrication system, and a system of channels and holes, the elastic membrane of lead into the drilling fluid. At the entrance to the wall of the mounting socket for the reservoir of the lubrication system, a small self-braking thread was made, in which two nuts were sequentially wrapped - an adjustment nut and a lock nut with holes on the ends for the socket wrench. As a pressing element, for example, a plate-shaped steel spring or an elastic ring of various cross-sectional shapes, for example round, can be used, which can compress under load and return to their original shape when the load is removed. The annular flat elastic collar of the membrane at its end is both an installation and compressive sealing element, pressed against the mating end continuous annular protrusion on the tank using an annular compressing element. A hole in the center of the spring and a system of gaps along its sides serve for free passage of flushing fluid under the inner surface of the elastic membrane. On the side surface of the reservoir channels are provided in the form of grooves and holes for the passage of lubricant under excessive pressure through a system of supply channels to the friction zones of bearings in bearings.

When the limit of excess pressure arising in the lubrication system occurs, the cup spring is wrung out.

Through the channels between the membrane stiffeners, then along the annular gap, which opens at excess pressure inside the lubrication system by compressing the elastic collar of the membrane and the disk spring under the protruding annular collar of the tank body and then through the system of holes and gaps provided between the reservoir and the annular collar of the membrane, the collar of the centering washer, in the gaps around the Belleville spring, and also through the hole in the suprahepatic space in the paw body, excess grease is removed from the grease system we, venting the pressure inside her. As soon as the pressure in the lubricating system and the pressure of the flushing fluid are equalized, the gap along the elastic surface of the annular collar of the membrane is closed due to the return pressing of the compressing element of the Belleville spring or elastic ring. In this case, the cycle of compensation of lubricant consumption in the support resumes again.

List of drawings

The figure 1 presents a fragment of the paw and the location of the tank.

The figure 2 presents a cross section of the tank mounted in the socket paws.

In figures 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12 shows a detail of the elements of the tank.

In the figure, 1 positions denote: 1 - the paw of the bit, 2 - the location of the socket for placing the reservoir for the lubricating system, 3 - the back of the paw, 4 - the direction of the lubricating channel in the paw from the outlet to the reservoir.

In the figure, 2 positions denote: 5 - tank body, 6 - elastic diaphragm, 7 - radial metal diaphragm frame, 8 - end metal frame, 9 - centering washer, 10 - disk spring, 11 - adjusting nut, 12 - lock nut, 13 - the thread on both nuts and on the tank wall, 14 - the first o-ring, 15 - the second o-ring, 16 - the hole in the foot connecting the socket to accommodate the tank with the annular suprahepatic space, 17 - conical shutter tube, 18 - ring groove to the outside the surface of the reservoir for the passage of lubricant, 19 - through holes in the housing, 20 - the inlet hole in the paw for transporting lubricant from the reservoir housing to the bearing heating zone, 21 - the central hole in the centering washer, 22 - the groove at the end of the washer, 23 - the radial clearance between tank body, diaphragm and centering washer, 24 - stiffeners on the elastic diaphragm 6, 25 - holes for the clamping socket wrench, 26 - holes for the clamping socket wrench in the lock nut.

In figures 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12, the elements on the detailing have the same designation as in figure 2.

The reservoir for the lubrication system of the drill bit with a sealed support is assembled and mounted on the finished bit after threading. To do this, on an annular protrusion in the tank body are sequentially installed: elastic diaphragm 6, made of rubber with radial 7 and end 8 metal frames. Following the diaphragm, a centering washer 9 is installed, made with a groove at the bottom and a lock on the side surface. Belleville spring 10 is installed at the bottom of the socket. O-rings are installed in the grooves on the side wall of the socket and the housing 5, together with the listed parts, is inserted from the bottom up into the socket 2 until it contacts the bottom. After turning the paw by turning the socket wrench, the adjusting nut presses the disk spring 10, the greater the clamping force of the elastic ring collar on the diaphragm created with the socket wrench, the greater the overpressure inside the lubrication system that could open the slot on the elastic ring collar to discharge overpressure.

Calibration and adjustment to the pressure at which the reservoir for the lubrication system of the drill bit with a sealed support should begin to relieve pressure at a particular depth, is carried out individually after assembly. To do this, the hose tip with the pressure of the liquid (or air) is wrapped instead of a conical stopper plug and imitates the pressure inside the lubrication system, gradually increasing it and, accordingly, they turn or unfold with the socket wrench at first the adjusting nut and the disk spring, simulating the conditions of the tank actuation on one or another depth while drilling a well. After setting the pressure on the manometer to the desired value, the position of the control nut is fixed with a lock nut individually for each section.

Then, the calibrated reservoir, adjusted to operate at the set pressure for the lubrication system of the drill bit with a sealed support, is mounted in the paw socket and fixed with a retaining steel ring 20.

Then, instead of the lid 17, a nozzle of the evacuation unit is screwed into the hole at the bottom of the tank, through which air is removed from the lubrication system, which is then forcibly filled with heat-resistant grease. Cover 17 is returned in place in all three sections of the bit. After painting and branding, the bit is ready to work.

Testing of prototypes of bits with the proposed reservoir for the lubrication system of a drill bit with a sealed support showed high reliability of its operation in drilling.

Information sources

1-2. Composite - catalog of OJSC Volgaburmash for 2003, p. 13.

3. Composite - catalog of the company "Smith" (USA) for 2000, p. 14.

Claims (1)

A cone drill bit with a sealed support containing legs, hermetically sealed and rigidly fixed lubricant reservoirs in them, elastic membranes with a radial and end metal frame, end ring centering washers, end compression elements, tapered threaded plugs, side grooves on the walls of the tanks with through holes for the release of grease from the reservoir cavity into the lubrication system, as well as a system of channels and holes for supplying elastic drilling fluid membranes, excellent This is because, on the outlet side of the nests in the paws, adjusting and locking nuts with holes on the ends for the socket wrench are installed on the thread, which regulate the efforts of pressing the elastic collar of the membrane, the end pressing element and the threshold for overpressure relief in the bit lubrication system.

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